January 17, 2013

Shocking Experiment Reveals That Crabs Really Do Feel Pain

Most cultures value the humane treatment and slaughter of their livestock, and now those same standards should be applied to their seafood, according to a new behavioral study published in the Journal of Experimental Biology.

The study, from Queen's University Belfast professors Bob Elwood and Barry Magee, exposed common shore crabs to electrical shocks and found those crabs responding to the shocks in a way consistent with experiencing pain.

"The experiment was carefully designed to distinguish between pain and a reflex phenomenon known as nociception,” said Elwood. “The function of pain is to aid future avoidance of the pain source, whereas nociception enables a reflex response that provides immediate protection but no awareness or changes to long-term behavior.”

"While nociception is generally accepted to exist in virtually all animals the same is not true of pain,” he added. “In particular, whether or not crustaceans experience pain remains widely debated."

To determine if the crabs would remember harm and avoid it in the future, they were tested to see if they would avoid a favored dark hiding place to avoid mild electric shocks that were subsequently placed there.

"Ninety crabs were each introduced individually to a tank with two dark shelters,” Elwood explained. “On selecting their shelter of choice, some of the crabs were exposed to an electric shock. After some rest time, each crab was returned to the tank. Most stuck with what they knew best, returning to the shelter they had chosen first time around, where those that had been shocked on first choice again experienced a shock.”

“When introduced to the tank for the third time, however, the vast majority of shocked crabs now went to the alternative safe shelter,” Elwood continued. “Those not shocked continued to use their preferred shelter.”

"Having experienced two rounds of shocks, the crabs learned to avoid the shelter where they received the shock,” he concluded. ”They were willing to give up their hideaway in order to avoid the source of their probable pain."

Elwood said his study could have implications for how we think about the seafood industry, possibly predicating a more humane treatment of crabs, lobsters, and prawns.

"Billions of crustacean(s) are caught or reared in aquaculture for the food industry,” he said. “In contrast to mammals, crustaceans are given little or no protection as the presumption is that they cannot experience pain. Our research suggests otherwise. More consideration of the treatment of these animals is needed as a potentially very large problem is being ignored.”

The study´s findings could also impact how we cook crustaceans in our home. The most common way to cook crabs is to plunge them into boiling water; however, many modern chefs are taking up the practice of stunning them beforehand.

"On a philosophical point it is impossible to demonstrate absolutely that an animal experiences pain,” Elwood said. “However, various criteria have been suggested regarding what we would expect if pain were to be experienced. The research at Queen's has tested those criteria and the data is consistent with the idea of pain. Thus, we conclude that there is a strong probability of pain and the need to consider the welfare of these animals."